When you connect to public Wi-Fi, like an airport, coffee shop, or a corporate guest network, you often see a web page asking you to sign in, accept terms, or enter a password before you can use the internet. This page is called a captive portal. Most captive portals ask you to agree to an Acceptable Use Policy (AUP).

Firefox's captive portal detector tests whether the network connection requires you to sign in or accept the network's terms before permitting you to use it. Sometimes the page doesn’t appear on its own, and you’ll need to open it manually to get online.

A captive portal is not limited to public Wi-Fi. It can also appear on a home, office, or wired network if a router, ISP, or network administrator requires a sign-in page before allowing internet access. In some cases, Firefox can detect a captive portal even when the network is not intentionally using one, for example when a router or network service redirects requests unexpectedly.

How Firefox detects captive portals

When Firefox detects that you’re connected to a network but not yet online, it will:

• Open the network’s sign-in page in a new tab.
• If the network uses a captive portal, Firefox will show a message such as, “You must log in to this network before you can access the internet.”

Once you complete the sign-in, Firefox will close the tab and your connection will work normally. If the page was left open by Firefox, you may simply close it. Occasionally, it will be kept around to display a message from the network's owners. If this happens frequently, please file a Networking bug and describe your case (requires creating a Bugzilla account).

Firefox tests if the connection is a captive portal by regularly connecting to http://detectportal.firefox.com/canonical.htmlhttp://firefox-portal-detection.com. Firefox will also make connections to this URL to check if your current network supports certain technologies such as IPv6.

A captive portal check does not by itself mean that your network is unsafe. It means Firefox detected that the network may need an additional sign-in or network step before normal internet access is available.

When can I ignore a captive portal message?

A captive portal message is usually expected when you're connecting to a network that requires you to sign in or accept terms, such as hotel, airport, library, or coffee shop Wi-Fi.

You can usually ignore or close the notification when:

• You have already completed the network's sign-in and your internet connection works normally.
• You are on a network you trust and the message disappears after reconnecting or refreshing.
• Your network administrator confirms that the network uses a captive portal or a similar sign-in system.

Do not enter passwords, payment information, or other sensitive information into an unfamiliar sign-in page just because Firefox shows a captive portal message. Check that you're connected to the network you intended to use and that the sign-in page belongs to the organization providing the network.

What do I do if the sign-in page doesn’t automatically appear?

If Firefox doesn’t show the page:

1. Try visiting any website, as most captive portals will redirect you to the sign-in page.
2. Disconnect and reconnect to the Wi-Fi network, then try again.

If you still can’t access the sign-in page after trying the above, you can try the following:

• Restart your device to refresh the network connection and trigger the sign-in page.
• Temporarily turn off any VPN or proxy until you’ve signed in.
• Open a new private browsing window to avoid cached sessions that might block the portal.

The best next step depends on the type of network you're using.

Public Wi-Fi

1. On a hotel, airport, café, library or other public network:
2. Make sure you are connected to the network's official Wi-Fi name.
3. Open a new tab and visit a simple website to trigger the sign-in page.
4. Disconnect from the network and reconnect.
5. Temporarily turn off a VPN or proxy and try again.
6. If the network requires you to accept terms or enter a room number, access code, or other information, complete that step before trying to browse normally.

If the portal still does not appear, contact the network operator or staff. The problem may be with the network rather than Firefox.

Home Wi-Fi or router

A captive portal can appear on a home network when your router, ISP or another network service redirects connections to a sign-in or setup page.

1. Restart your modem and router.
2. Check whether other devices on the same network can access the internet.
3. Open your router's administration page and check for a required login, setup step or internet connection warning.
4. Check whether your ISP requires you to sign in or confirm your service.
5. If every device shows the same captive portal or cannot access the internet, the problem is likely with the router, ISP or network rather than Firefox.

If other devices can browse normally but Firefox continues to show a captive portal message, continue with the troubleshooting steps below.

Wired connection

Captive portals are not limited to Wi-Fi. A workplace, school, hotel, or other network can require a sign-in even when your device is connected with an Ethernet cable.

1. Check whether the network requires a sign-in or Acceptable Use Policy.
2. Try opening a website to trigger the sign-in page.
3. Ask the network administrator whether access is restricted until you sign in.
4. If other wired devices have the same problem, the network administrator or ISP may need to resolve it.

VPN or proxy

A VPN or proxy can prevent Firefox from reaching a captive portal correctly because the network may need you to sign in before the VPN or proxy connection can be established.

1. Temporarily turn off your VPN or proxy.
2. Reconnect to the network.
3. Open a website and complete the captive portal sign-in.
4. Turn the VPN or proxy back on after you have internet access.

If the captive portal works only when your VPN or proxy is disabled, check the VPN or proxy provider's documentation for captive portal support.

Firefox keeps detecting a captive portal

Sometimes Firefox may continue to detect a captive portal even though you can already browse the web. This can happen when the network redirects the connection in an unexpected way or when captive portal detection receives an unusual response.

1. Confirm that you can open normal websites.
2. Disconnect and reconnect to the network.
3. Restart Firefox.
4. Temporarily disable a VPN or proxy and test the connection again.
5. Check whether other devices on the same network show the same behavior.
6. If the message appears repeatedly on a network without a normal sign-in page, contact the network administrator or ISP to ask whether the network redirects captive portal detection requests.

If this happens frequently and you believe Firefox is detecting the network incorrectly, please file a Networking bug with details about the network and what you see.

Privacy and captive portal detection

Firefox checks whether you are behind a captive portal by making periodic network requests. These checks help Firefox determine whether it should open a network sign-in page.

These checks are part of Firefox's network connectivity behavior. They do not mean that Firefox sends your browsing history or the contents of the websites you visit to the captive portal detection service.

For technical details about how captive portal detection works, see Captive Portal Detection in Firefox Source Docs.

Related articles

• Joining public WiFi while on Mozilla VPN
• How to stop Firefox from making automatic connections
• Captive Portal Detection in Firefox Source Docs